The present invention relates to the field of optical devices and methods for their fabrication. Particularly, the present invention is concerned with sources and detectors for single photons.
In a particular type of photon source and/or detector, it is desirable to fabricate an optical cavity with a narrow effective lateral area. It is also necessary to be able to apply a bias across the optical cavity. These two aims can conflict with one another since it is difficult to reliably fabricate a device where electrical contact is made to a cavity which has a narrow effective lateral area.
One technique has involved for an optical cavity with a restricted size by patterning the mirrors above and below the cavity. Examples of this technique are described in Choquette et al., Proceedings of the IEEE 85, pages 1730 to 1739 (1997), Choquette et al., IEEE Journal of Selected Topics in Quantum Electronics 3, pages 916 to 926 (1997), Iga, IEEE Journal of Selected Topics in Quantum Electronics 6, pages 1201 to 1215 (2000) and Chua et al, IEEE Photonics Technology Letters, 9 pages 551 to 553 (1997) where the mirrors are oxidised in order to reduce the effective size of the cavity without reducing the actual size of the device to allow easy contact.
E. R. Brown et al., IEEE Transactions on Microwave Theory and Techniques, 40 pages 846 to 850 (1992) describes technique for making electrical contact to a semiconfocal open cavity resonator. Electrical contact is achieved by using a metal whisker.
Transport based devices tend to be easier to fabricate than optical devices since they do not require an optical cavity to be defined in addition to any means for restricting the sport of carriers through the device. Jones et al. IEEE Transactions on Microwave Theory and Techniques 45, pages 512 to 518 (1997) describe a varactor transport device where contact is made between a contact pad and anode using a metal air-bridge finger. A metal whisker is used to make contact to another varactor in Raisanen, Proceedings of the IEEE 80, pages 1842 to 1852 (1992).
Randall et al. J. Vac. Sci. Technol. B6, pages 302 to 305 (1987) describes resonant tunnelling diode transport devices formed by etching narrow pillars.